Weight Management and Disordered Eating

what composes total energy expenditure

• basal metabolic rate; cost of keeping us alive

• voluntary activity

• thermic effect of food; cost of making food into a product that the body can use

proportions of BMR, activity and TEF in TEE

• BMR is the largest, taking up to about 75%

• activity is about 15%

• TEF is about 10%

which is the easiest vs hardest to measure

• activity is the most straightforward to measure

• TEF is the hardest to measure due to being multifactorial

what factors affect TEF

• meal size

• meal composition (there is higher TEF for proteins and carb vs lipids)

• meal frequency, timing, education

• factors that can affect BMR can also affect TEF such as body composition, age, etc.

difference in TEF between obese vs lean individuals

TEF seems to be reduced in obese individuals as there seem to be small increase in metabolic rate compared to lean individuals when eating

factors that affect basal metabolic rate

• height and weight= BMI

• sex (%fat vs muscle mass [decrease BMR for fat vs muscle; more fat in women than men], hormones)

• age/development/lifestage (pregnancy, lactation, infancy, childhood, adolescence, adulthood, senior)

• hormone levels such as thyroid hormone

• stress, fever, illness

• other genetic factors

• effects of medication and other compounds such as caffeine

• fed, fasted or starved energic state

external and internal cues for energy intake

external cues

• time of day

• food availability

• food quality

• social norms and influences

internal cues

• hunger and satiety

• emotions such as stress or boredom

ghrelin

hunger hormone- produced by stomach increases drive to eat

vagus nerve

connects brain and digestive system (PSNS). stimulation by stretching the stretch receptors decreases appetite

leptin

energy expenditure hormone- is a protein hormone made by adipocytes. its levels correlate with energy reserves (stored triglycerides). leptin inhibits hunger, to stimulate satiety

GLP-1 (glucagon-like peptide-1)

produced by the large intestine and ileum. decreases blood glucose by increasing insulin and decreasing glucagon and decreases appetite by slowing gastric emptying

CCK (cholecystokinin)

peptide hormone that stimulates the digestion of fat and protein. secreted by duodenum in the small intestine

insulin

peptide hormone secreted by beta-cells in the pancreas. induces uptake of glucose into body cells (+other functions), reduces hunger

what is involved in anticipatory signaling

• GLP 1 peaks 1 hour before a meal returns to baseline by meal start

• ghrelin builds over time and declines with feeding

• insulin increases just before mealtime and in response to blood glucos

obesity is affected by what factors

• increases with age

• lower risk with increasing education

• lower risk in landed immigrants vs non immigrants due to cultural factors

• dietary pattern (5+ fruits or vegetables per day reduces the risk)

obesity and T2DM relationship

• chronic inflammation contributes to the development of insulin resistance in tissues

  • larger adipocytes in obesity attract macrophages by secreting macrophage chemotaxis protein

  • macrophages produces pro inflammatory TNFa

  • TNFa induces export of FFA into the blood leading to increased FFA in body

  • muscle imports the excess FFA from the blood, which builds up as ectopic lipid droplets by embedding themselves in muscles

  • ectopic lipid droplets interfere with GLUT-4 translocation leading to insulin resistance

• increased use of FFA=increased toxic byproducts; damage to beta-cells of pancreas and insulin insufficiency

obesity and CVD

• obesity increases the risk of dyslipidemia; high TG, high VLDL, high LDL and low HDL

• LDL can penetrate vessel walls, become oxidized and form a plaque

  • high levels of VLDL in obesity prevent normal metabolism of lipoproteins, leading to abnormal transfer of cholesterol and triglycerides between lipoproteins 

  • production of new lipoproteins enriched with triglycerides (VLDL-TG and LDL-TG). enriched lipoproteins can be converted into small dense-LDL (sd-LDL) by hepatic lipase

  • sd-LDL is like normal LDL but worse- better at penetrating artery walls, longer residence time in the blood, more susceptible to oxidation

limits of BMI as a measurement

• muscle weighs much more than fat, so muscular individuals have higher BMI than expected

• it only considers weight and heigh

• does not factor in lean muscle mass vs adipose tissue

• does not consider location of adipose tissue (visceral vs subcutaneous) varies across subpopulations and subcutaneous better predicts some comorbidities

• ignores metabolic markers of disease risk and mental health component of obesity

alternative to BMI

EOSS (Edmonton obesity staging system)

• more comprehensive rating scale that includes physical and psychological symptoms as well as functional limitations

• focuses on associated health problem and their severity vs weight

stages of EOSS

stage 0= obese, but no risk factors present, no action or preventative options only

stage 1= subclinical risk factor(s) present, preventative options only

stage 2+= at least one established risk factor; specific nutritional, lifestyle, surgical and/or pharmacological action needed

lifespan of adipose cells

9.5 years

weight cycling

• weight loss = decreased leptin = increased energy intake and decreased energy expenditure

  • BMR decreases

  • activity decreases

  • making it easier to regain positive energy balance, allowing adipose cells to refill

• weight gain= increased leptin = decreased energy intake and increased energy expenditure

behavioural modification

• may include CBT or cognitive behavioural therapy

• preparatory phase= assess the nature and severity of obesity and any medical or psychosocial comorbidities

• phase 1= initial weight loss including changing eating patterns, activity

• phase 2= long-term weight maintenance phase focusing on locking in new habits, tapering off monitoring 

general recommendations for dietary modification

• high protein to promote satiety

• water as a drink of choice

• nutrient dense as opposed to energy dense food

• reduced processed foods

• substitutions as opposed to eliminations

fad diets

is a plan that promotes results such as fast weight loss without robust scientific evidence to support its claim

weight loss pharmacotherapy

• orilstat- pancreatic lipase inhibitor limits fat absorption

• liraglutide and semaglutide- GLP1 agonist reducing appetite

• naltrexone and bupropion- hunger suppression

• side effects

  • headache

  • dizziness

  • fatigue

  • GI disruption

  • hypoglycemia

  • gallbladder problems

  • pancreatitis

weight loss surger

• gastric band

• gastric bypass

• sleeve gastrectomy

DSM-5TR of feeding and eating disorder

a disorder characterized by a persistent disturbance of eating or eating-related behaviour that results in the altered consumption or absorption of food and that significantly impairs physical health or psychosocial functioning 

causes of feeding and eating disorder

• multifactorial

• psychological and sociocultural combine to develop a distorted body image

• genetics can play with traits such as perfectionism and the baseline body type, hunger and satiety

• changing social pressures

anorexia nervosa

persistent restriction of energy intake that leads to significant low body weight

bulimia nervosa

repeated binging episodes with a feeling of lack of control overeating and repeated compensation after eating by vomiting, misuse of laxatives, or excessive exercise to prevent weight gain

binge eating disorder

repeated binging episodes with a feeling of lack of control overeating but not repeated compensation after eating by vomiting, misuse of laxatives, or excessive exercise to prevent weight gain

anorexia athletica

eating disorder characterized by excessive and compulsive exercise which is particularly high in sports where a thin body is preferred- figure skating, ballet, gymnastics, dancing, skiing and other events

female athlete triad

disordered eating due to pressure to maintain lean, thin and athletic bodies leading to

1. energy restriction paired with excessive exercise can upset hormonal balance

2. low estrogen levels can lead to amenorrhea

3. low food intake and low estrogen can impact nutrient intake especially calcium